'80G Idle Mixture Screw Extraction Tips?

[Phil_G]

Hi all!

I'm in the process of rebuilding the carbs on my 80G.
PO stripped the slots on the idle mix screws by using the wrong sized tooling.

I just picked up an "EZ out" kit, and drill bits...

I have the new screws to reference for size...

My plan is to take a large bit the same size as the head of the screw--and to make a good, clean center mark on the heads (without getting into the aluminum of course)... and then to use that center to start the pilot hole for an "EZ out," let them cool after drilling, soak with Kroil, and give it a go at backing those puppies out.

Does anyone have experience in doing this?
Any helpful tips, or links I should check out?

--I did a search for about 15 minutes, and I think I was too specific in my wording?--


THANKS IN ADVANCE!!!!

[DiverRay]

I used a cut-off blade on a dremel and took out the aluminum around the screw! You can cut around most of the tower, and that should give you the room to cut a "new" slot in the screw with the dremel and remove it. I would also take the tower down to the thread area, so water will not build up in there(if you ride in the rain).

[DGXSER]

I tried this route with one that was stuck and boy did I pay the price. The extractor broke off in the screw. I wound up taking it to a machine shop who milled it out to the minor diameter of the threads and I carefully peeled out the remaining material from the threads.

I would suggest soaking them in any kind of good penetrating oil for a day or two. Then try to use a dremel to mill a new screwdriver slot in the screw. Now take off all you can from that area, I back out the rubber seal for the enrichment plunger. Then heat the tunnel REALLY good till the oil smokes out of it, add oil again, soak, heat again. After a few cycles, try to turn the screw. I would get a set of left handed drill bits and try those first, extractor would be my last choice.

[Phil_G]

I didn't even think of cutting out the material above them to gain access! I wasn't thinking outside of the box apparently

Thank you guys!

It'll be a week or two before I get a chance to get to the garage and work on them--But I'll be sure to let ya know how they turn out.

much appreciated!!!

[Ken Talbot]

I solved this one by using a small diamond burr in a dremel tool to cut the new slot directly in the screw without damaging the aluminum collar. Then I ground a screwdriver bit down to fit and used an impact driver to loosen the screw. I believe that screw is still in service.

[Phil_G]

progress thus far

I took into account all of your guys' advice.

I pieced together my new arsenal of tools: propane torch, dremel, diamond bits, the works

the carving out of new driver slots became a combination of a few of your previously mentioned horror stories...

I cut a new slot in the first screw, without disturbing the aluminum tower above it.. then narrowed down an impact driver bit to size... got out the PB Blaster, torch, pan of boiling water, and even used the freezer to make the temperature changes more drastic.

The brass was SO old and brittle that it flaked apart on the first attempt to use the impact driver.

Fearing that the extension of the screw bore was in the way--I removed that... then repeated the process of heating, cooling, cleaning, lubing, and extracting. again... slot wiped off.

I was cutting slots deep enough that there should have been plenty of meat to grab a hold of... oh well, right?

I ended up improvising after 5 tries...

I used a barrel shaped diamond bit. guessed my center, kept it square, and hogged out the brass until I saw aluminum appear-- a LOT of grind-and-check. It turns out I was dead on center, I managed to remove enough material that the spring and screw tip came out before the threaded stuff!!

I basically had to recreate your scenario, DGXSER, and ground the brass out until I saw the threads appear--then peeled out the remaining brass ribbons.

I wouldn't say proud, but I will say relieved, to announce that I should only need a tap to clean up the threads!!!


All that to ask one little question, anyone know off hand the tap size/pitch I'll need to clean those up? more so--where did anyone find theirs? It looks like a fine pitch, and like every other part in those bodies, I'm guessing metric...

I'm getting ready to go on a tool run and want to make it a quick mission.


Again, thanks for all of your helpful advice earlier--it was ALL put to good use!!!!!

Phil

[DGXSER]

Not sure the exact size, I was just trying to find that the other day and relized none of the thread gages I have are small enough. but I almost guarantee you will not find it locally. Probably have to order it.

[Phil_G]

I think I'll try the local hardware store for a hardened bolt of the same thread.

I'll make a tap by running a nut onto the bolt before tapering the tip of the bolt, then grinding in chip grooves... I'll clean those threads up by running the nut up/down the bolt a few times... It won't be any cheaper... but it's local... and could be good practice...

[T.Montagno]

i'm next

I have my 79 xs 1100 carbs on my bench waiting to rebuild , is cleaning the jet and orifice and having a proper operating float satisfactory for reinstallation,Tom

[DGXSER]

I would highly recommend reading through the Carb Cleaning 101 thread that Wildkat put together. Do a search for it. It incorporates alot of great knowledge!!

Ohh, and the tool that Ken Talbot has detailed how to make for float pin removal, another search to be done to find it, that is the Shizzle!!! Saved me a few broken float post I am certain!!!

[Phil_G]

Not sure the exact size, I was just trying to find that the other day and relized none of the thread gages I have are small enough. but I almost guarantee you will not find it locally. Probably have to order it.

I took my replacement screws to Fastenal, they were able to source an M6-0.5 tap at their main hub... for about $6!!!! I ordered 2.

[DGXSER]

Hmmm...sounds like an investment I might make. Could turn at least three scrap carb bodies into viable pieces for future use.

[DiverRay]

Fastenal, they were able to source an M6-0.5 tap

Are you SURE of that size! M6 is the size of the case screws. I think the mixture screws are an M4 or M3.5!

[Phil_G]

I'm pretty sure... I let the manager measure the screws against the diameter checker, and then with the pitch gage... he came across as competent...

If it comes back as the wrong size, I'll know by tomorrow or wednesday. and I'll be sure to update as soon as i can.

[Phil_G]

Status report:

m6 x 0.5 is the correct tap size! Whew!!
-----------------------------

Oh, I got all 4 of those screws out! the screws didn't survive... but the carbs did

I took a bit the size of the ID of the bore, centered the heads of the screws, then took a 5mm bit and drilled straight through.

the tips and springs can then be pushed out through the hole.

next step was to ream out the holes with a burr bit, just big enough to start the tap...

the tap helped to clean out the old brass...

all in all... I'd say I'm pleased with the results so far.